Regenerative oxidizer assembly for use in pem fuel cell applications

ABSTRACT

A method of using a catalyst body able to support gas flow therethrough and having a catalyst for promoting a catalytic reaction of a component of a first gas and being able to be regenerated by a second gas, comprising: providing at least the first gas and the second gas; and repeatedly moving successive parts of the catalyst body into communication with the first gas and then into communication with the second gas; wherein: the part of the catalyst body in communication with the first gas causes the component of the first gas to be reacted as the first gas passes though and exits the part of the catalyst body; and the part of the catalyst body in communication with the second gas has the catalyst of that part regenerated as the second gas passes through and exits the part.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of application Ser. No. 12/131,483,filed Jun. 2, 2008, which, in turn is a divisional of application Ser.No. 10/916,202, filed Aug. 11, 2004, now U.S. Pat. No. 7,381,488, theentire disclosures of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

This invention relates to oxidizer assemblies and, in particular, tooxidizer assemblies for use in proton exchange membrane (“PEM”) fuelcell applications.

In copending application U.S. Ser. No. 10/894,993, filed Jul. 20, 2004,entitled OMS-2 Catalysts in PEM Fuel Cell Applications, there isdisclosed an oxidizer assembly which utilizes an OMS (“octahedralmolecular sieve”)-2 catalyst to oxidize the carbon monoxide in the fuelfeed to a PEM fuel cell. As described therein, OMS-containing materials,such as synthetic todorokite (Mg²⁺ _(0.98-1.35)Mn³⁺ _(1.89-1.94)Mn⁴⁺_(4.38-4.54)O₁₂ 4.47-4.55H₂O) or cryptomelane (K-hollandite,KMn₈O₁₆nH₂O), comprise manganese oxide octahedral compounds linked byedges and vertices and forming uniform tunnels therethrough. OMS-2catalysts are manganese oxide octahedral molecular sieves possessing the2×2 tunnel structure (as in the aforementioned cryptomelane).

The '993 application specifically describes transition metal cationdoped OMS-2 catalysts which can be framework-substituted andtunnel-substituted molecular sieves which are referred to by thedesignations [M]-OMS-2 and [M-OMS-2], respectively, where M indicatestunnel or framework-substituted metal cation(s) other than manganese.Specifically disclosed in the application as preferable catalysts areCo-OMS-2, Cu-OMS-2 and Ag-OMS-2, with Ag-OMS-2 being most preferable.

The '993 application also describes the operation of the OMS-2 catalystto cause selective oxidation of the carbon monoxide in the feed to a PEMfuel-cell as occurring chemically via a sorption-chemical oxidationprocess aided by the unique pore structure and active sites of thecatalyst. In particular, the sorption-chemical oxidation process at lowtemperatures is described as a two stage process, a sorption stage and achemical oxidation stage. As stated therein, during the sorption stage,carbon monoxide is selectively adsorbed on the metal active side of theM-OMS-2 (Ag-OMS-2) catalyst as follows:

Ag*+CO→CO_(ad)  (1)

This process then proceeds to the chemical oxidation stage in whichcarbon monoxide is chemically oxidized with oxygen typically present inthe OMS-2 tunnel or provided with the fuel feed or reformate gas.Specifically, oxygen from the OMS-2 tunnel is released in the followingreaction:

O-OMS-2→OMS-2+½O ₂  (2)

Subsequently, carbon monoxide is oxidized by reacting carbon monoxidewith the released oxygen to produce carbon dioxide in the followingreaction:

CO_(ad)+½O₂→CO₂+Ag*  (3)

Following the sorption-chemical oxidation reaction, the OMS-2 can beregenerated in situ by adding oxygen from a feed gas to produce anO-OMS-2 regenerative substrate. This reaction is as follows:

OMS-2+½O₂→O-OMS-2  (4)

The oxidizer assembly incorporating the OMS-2 catalyst is described inthe '993 application as being capable of performing the oxidation andthe regeneration processes simultaneously. In particular, an oxidizerassembly is disclosed in which parallel packed bed reactors each havingan M-OMS-2 catalysts are operated so that one reactor is performingcarbon monoxide oxidation of the PEM fuel cell feed gas, while the otherreactor is having its M-OMS-2 catalyst being regenerated. While thistype of oxidizer assembly is usable, a more compact and simpler oxidizerassembly is desired.

It is therefore an object of the present invention to provide anoxidizer assembly for oxidizing the carbon monoxide in a feed gas whichis simple and compact in configuration.

It is a further object of the present invention to provide an oxidizerassembly of the above-mentioned type which is also capable of allowingin situ catalyst regeneration without interrupting the oxidation ofcarbon monoxide.

SUMMARY OF THE INVENTION

In accordance with the principles of the present invention, the aboveand other objectives are realized in an oxidizer assembly provided witha housing having a plurality of inlets each for receiving a differentgas and a plurality of outlets. Each of the outlets corresponds to adifferent one of the inlets and outputs gas resulting from the gasreceived from its corresponding inlet. A catalyst assembly able tosupport gas flow therethrough is disposed within the housing andincludes a catalyst able to oxidize carbon monoxide gas and to beregenerated. The catalyst assembly is further adapted to be movable suchthat successive parts of the assembly are able to be brought repeatedlyin communication with a first inlet and its corresponding first outletand then a second inlet and its corresponding second outlet of thehousing. In the preferred form of the invention, the catalyst assemblyis additionally adapted so that each section is brought in communicationwith a third inlet and its corresponding outlet after being incommunication with the second inlet and its corresponding second outletand prior to being brought back into communication with the first inletand its corresponding outlet.

In this way, by supplying a feed gas with carbon monoxide to be oxidizedto the first inlet, an oxidant gas to the second inlet and a cooling gasto the third inlet, the following occurs with respect to each region ofthe catalyst assembly: when in communication with the first inlet, theregion receives the feed gas and oxidizes the carbon monoxide in thefeed gas as the feed gas passes therethrough to the first outlet; whenin communication with the second inlet, the region receives the oxidantgas and as the oxidant gas passes therethrough to the second outlet thecatalyst in the region is regenerated; and when in communication withthe third inlet, the region receives the cooling gas and is cooled asthe cooling gas passes to the third outlet. This process is thenrepeated as each region of the catalyst assembly is brought repeatedlyin communication with the first, second and third inlets.

In the form of the invention to be disclosed herein, the catalystassembly comprises a porous body coated with an OMS-2 catalyst. Also, ina first embodiment of the invention to be disclosed herein, the porouscatalyst body is rotatable within the housing and has first and secondends along its axis of rotation which abut and seal against, but rotaterelative to, first and second sealing members, respectively. The firstand second sealing members, in turn, abut first and second end walls ofthe housing which have the inlets and the outlets, respectively. In thiscase, the sealing members define at least first, second and third inletmanifolds which communicate with the first, second and third inlets,respectively, and corresponding first, second and third outlet manifoldswhich communicate with the first, second and third outlets,respectively, and at any given time the regions of the rotatablecatalyst body in line with the respective inlet manifolds and theircorresponding outlet manifolds are sealed from one another. As thecatalyst body rotates, these regions change so that all parts of thecatalyst body are repeatedly moved to communicate with the first, secondand third inlet manifolds and thus the first, second and third inlets.

In a second embodiment of the invention, the porous catalyst body isalso rotatable within the housing and is configured to define regionssealed from each other and which at first and second ends along the axisof rotation of the catalyst body communicate with first and second endwalls of the housing which have, respectively, the inlets and outlets ofthe housing. As the catalyst body rotates, the regions move so that theyare brought repeatedly into communication with the first, second andthird inlets, while remaining sealed from each other.

In the above embodiments, the rotatable catalyst body is in the form ofa honeycomb ceramic corderite structure with through passages.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and aspects of the present invention willbecome more apparent upon reading the following detailed description inconjunction with the accompanying drawings, in which:

FIG. 1 shows a PEM fuel cell system using an oxidizer assembly foroxidizing carbon monoxide in accordance with the principles of thepresent invention;

FIG. 2 shows the oxidizer assembly of FIG. 1 in greater detail;

FIG. 3A shows a cross-sectional view taken along the line 3A-3A of FIG.2 of a first embodiment of the oxidizer assembly of FIG. 2;

FIG. 3B shows a cross-sectional view taken along the line 3B-3B of FIG.2 of the first embodiment of the oxidizer assembly of FIG. 2;

FIG. 3C shows a cross-sectional view taken along the line 3C-3C of FIG.2 of the first embodiment of the oxidizer assembly of FIG. 2;

FIG. 4A shows a cross-sectional view taken along the line 4A-4A of FIG.2 of a second embodiment of the oxidizer assembly of FIG. 2;

FIG. 4B shows a cross-sectional view taken along the line 4B-4B of FIG.2 of the second embodiment of the oxidizer assembly of FIG. 2;

FIG. 4C shows a cross-sectional view taken along the line 4C-4C of FIG.2 of the second embodiment of the oxidizer assembly of FIG. 2;

FIG. 5 shows a representation of a ceramic honeycomb corderite substratefor use in the oxidizer assembly of FIG. 2;

FIG. 6 shows an SEM representation of an Ag-OMS-2 catalyst coated on thesubstrate of FIG. 5;

FIG. 7 shows a graph of performance data of coated substrate samples ofFIG. 6 tested in a microreactor over a period of time; and

FIG. 8 shows a diagram of the operation of the oxidizer assembly of FIG.2.

DETAILED DESCRIPTION

FIG. 1 shows a PEM fuel cell system in accordance with the principles ofthe present invention. As shown, the system 1 comprises a PEM fuel cell2 having an anode section 2 a and a cathode section 2 b separated by aPEM 2 c. A fuel supply 3 provides a hydrocarbon fuel, such as, forexample, natural gas, gasoline or methanol, to a reformer unit 4 whichconverts the hydrocarbon fuel to a PEM fuel feed or reformate which isrich in hydrogen. The fuel feed also contains substantial levels ofcarbon monoxide gas, typically greater than 20,000 ppm.

The PEM fuel cell feed from the reformer 4 is then passed through a lowtemperature shift reactor 5 in which a portion of the carbon monoxidegas is converted to carbon dioxide, thereby reducing its level,typically to about 2,000 ppm. An oxidizer 6 follows the shift reactorand is adapted to oxidize a further portion of the remaining carbonmonoxide in the PEM fuel cell feed so that the level of carbon monoxideis less than about 20 ppm. The resultant PEM fuel cell feed is thendelivered from the oxidizer to the anode section 2 a of the PEM fuelcell 2, whereby the fuel undergoes electrochemical reaction with theoxidant supplied to the cathode section 2 a of the fuel cell to therebyproduce electrical energy.

As is also shown, an oxidant supply assembly 7 supplies oxidant to theoxidizer 6 for regenerating the catalyst of the oxidizer. A cooling gassupply assembly 8 further supplies a cooling gas to the oxidizer forcooling the oxidizer. These operations will be further describedhereinbelow.

The oxidizer 6 is adapted to oxidize the carbon monoxide in the PEM fuelfeed in such a manner as to readily handle transients in the level ofcarbon monoxide and with limited hydrogen consumption. This is realized,as discussed in the '993 application by using an OMS-2 catalyst as anoxidizing catalyst in the oxidizer 6. As previously discussed, OMS-2catalysts are octahedral molecular sieves of, as, for example,cryptomelane (K-hollandite, KMn₈O₁₆nH₂O). The OMS-2 catalysts thuscomprise manganese oxide octahedral compounds linked by edges andvertices and forming uniform tunnels therethrough. As also previouslydiscussed, metal cations may be incorporated in the tunnels of the OMScompounds.

As stated in the '993 application, the preferable OMS-2 catalysts forthe oxidizer 6 are metal cation doped OMS-2 catalysts, i.e., M-OMS-2catalysts. Preferable M-OMS-2 catalysts are Co-OMS-2, Cu-OMS-2 andAg-OMS-2, with Ag-OMS-2 being most preferable.

FIG. 2 illustrates a form of the oxidizer assembly 6 in accordance withthe principles of the present invention. As shown in FIG. 2, theoxidizer assembly 6 includes a catalyst assembly 104 having a catalystbody 104 a which is enclosed within a housing 102. The housing 102,shown as cylindrical, has a first end wall 106 a and a second end wall106 b. The first end wall 106 a has a plurality of inlets 108 a, 110 aand 112 a and the second end wall 106 b a plurality of correspondingoutlets 108 b, 110 b and 112 b.

The inlets 108 a, 110 a and 112 a are adapted to receive, respectively,the reformed fuel feed containing carbon monoxide from the shift reactor5, the oxidant gas from the oxidant supply 7 for regeneration of thecatalyst of the catalyst body 104 a, and a cooling gas from the supply 8for cooling the regions of the catalyst assembly which have had theircatalyst regenerated. The outlets 108 b, 110 b and 112 b, in turn,convey from the housing the gases received in the corresponding inlets108 a, 110 a and 112 a after the gasses have passed through the catalystassembly 104.

As also shown, the oxidizer assembly 6 includes a drive shaft 114 forrotating the catalyst body 104 a. This rotation brings each region ofthe catalyst body repeatedly into communication with the inlets 108 a,110 a and 112 a and their corresponding outlets 108 b, 110 b and 112 b.

As can be appreciated, therefore, at any given time, the catalyst body104 a is simultaneously oxidizing carbon monoxide gas in the fuel feedin a first region of the body communicating with the inlet 108 a and itscorresponding outlet 108 b, is having its catalyst regenerated byoxidant gas received in a second region of the body communicating withthe inlet 110 a and its corresponding outlet 110 b, and is being cooledby a cooling gas in a third region of the body communicating with theinlet 112 a and its corresponding outlet 112 b. Moreover, as will bediscussed in greater detail hereinbelow, the catalyst assembly 104 isfurther adapted such that the aforementioned first, second and thirdregions of the catalyst body are sealed from one another so that thegases delivered to and exiting from these regions do not mix with eachother. Additionally, as the catalyst body rotates, the regions change sothat all parts of the catalyst body come into communication with thefirst, second and third inlets and this process is continuouslyrepeated.

FIGS. 3A-3C illustrate detailed cross-sectional views of a firstembodiment of the oxidizer assembly 6 of FIG. 2. These cross-sectionsare taken along the lines 3A-3A, 3B-3B and 3C-3C of FIG. 2. As shown inFIGS. 3A and 3B, the catalyst body 104 a of the catalyst assembly is aone-piece substantially cylindrical porous structure with a circularcross-section. In the present case, the catalyst body is made porous viaapertures 104 ac extending therethrough between a first end 104 aa andan opposing second end 104 ab of the body. The catalyst body is alsoattached to the shaft 114 so as to be rotatable within the cylindricalhousing 102. Typically, the housing 102 can be formed as a stainlesssteel canister and the catalyst body 104 a as a ceramic honeycombcorderite monolith or structure having a catalyst coating, as describedin more detail below.

The first and second end walls 106 a and 106 b of the housing 102 areformed as separate covers which fit into the respective open oppositeends of the housing 102 so as to close the housing and cover thecatalyst body 104 a and other components of the assembly 6 containedwithin the housing. In the particular case shown, each end wall 106 a,106 b extends a short distance into the housing along the housing innerwall so as to fully cover the respective opening. Each end wall cantypically be formed from a glass filled Teflon® material, although otherhigh-temperature polymer materials, such as Viton® or PVA-based rubber,can also be used.

As is also shown, the drive shaft 114 passes through the length ofoxidizer assembly 6 from the outer surface of the second end wall 106 bto above the outer surface of the end wall 106 a. The shaft is rotatablyheld and the catalyst body 104 a is attached to the shaft so as torotate therewith. Accordingly as the shaft is rotated by an actuatorassembly (not shown) engaging the end of the shaft extending beyond thefirst end wall 106 a, the catalyst body 104 a also rotates within thehousing 102.

In the present case, the catalyst assembly 104 further comprises a firstsealing member 116 a followed by a first gasket member 118 a positionedbetween the first end 104 aa of the catalyst body 104 a and the firstend wall 106 a, and a second sealing member 116 b followed by a secondgasket member 118 b positioned between the second end 104 ab of thecatalyst body 104 a and the second end wall 106 b. The sealing member116 a, the gasket member 118 a and the end wall 106 a are held togetherby a plurality of fastening members 120 a. Like fastening members 120 bhold the sealing member 116 b, the gasket member 118 b and the top plate106 b together. As can be appreciated, the combined unit of each endwall, gasket member and sealing member is fixed in place with respect tothe container unit 102 and is not driven by the driving shaft 114.

Each gasket member 118 a, 118 b is disc shaped and includes threethrough openings aligned with the inlets or outlets in the adjacent endwall. In particular, as shown in FIG. 3C, the gasket member 118 aincludes through openings 126 a, 128 a and 130 a aligned with theopenings 108 a, 110 a, 112 a in the first end wall 106 a. The gasketmember 118 b similarly is disc shaped and includes three throughopenings 126 b, 128 b and 130 b (not visible) aligned with the openings108 b, 110 b and 112 b in the second end wall 106 b.

In the case shown, the inlets 108 a, 110 a and 112 a are circular and ofthe same size. Likewise, the outlets 108 b, 110 b and 112 b are circularand of the same size as each other and as the inlets. Additionally, eachof the through openings 126 a, 126 b, 128 a, 128 b, 130 a and 130 b iscircular and of the same size as the adjacent inlet or outlet. It shouldbe noted, however, that the inlets, outlets and openings need not all beof the same size and shape and that these parameters can be varieddepending upon the particular application and circumstances.

The sealing members 116 a and 116 b define first, second and third inletmanifolds and corresponding first, second and third outlet manifoldswhich are sealed from each other and which communicate with therespective through openings and inlets and outlets in the adjoininggasket members and end walls. At any given time, the three inletmanifolds and corresponding three outlet manifolds encompass threeadjacent regions of the catalyst body 104 a so that the gases passinginto, through and out of each region are sealed form each other and donot mix.

As shown in FIG. 3C, the sealing member 116 a defines three inletmanifolds 122 a, 124 a and 132 a which are sealed from each other andalign with the through openings 126 a, 128 a and 130 a in the gasket 118a and the inlets 108 a, 110 a and 112 a in the end wall 106 a. Thesealing member 116 b is similar and defines three outlet manifolds 122b, 124 b and 132 b (not visible) which are sealed from each other andalign with the through openings 126 b, 128 b and 130 b in the gasket 118b and the outlets 108 b, 110 b and 112 b in the end wall 106 b.

In the illustrated case, the sealing member 116 a comprises a circularouter part in the form of a ring 116 aa which abuts the portion of theend wall 106 a adjacent the inner wall of the housing 102. An inner part116 ab of the sealing member is Y-shaped and has three segments or arms116 ac, 116 ad and 116 ae which extend radially inward from the ring 116aa to a central hub part 116 af through which the shaft 114 passes. Ascan be appreciated, the open regions between the arms 116 ac-116 aedefine the inlet manifolds 122 a, 124 a and 132 a. The sealing member116 b is similarly constructed thus defining the corresponding outletmanifolds 122 b, 124 b and 132 b.

With this design for the sealing members, at any given time, threeregions of maximum area of the catalyst body 104 a are exposed,respectively, to the three inlets 108 a, 110 a ad 112 a and theircorresponding outlets 108 b, 110 b and 112 b of the oxidizer assemblyand these three regions are sealed from each other by the sealingmembers 116 a and 116 b. As a result, the catalyst body issimultaneously oxidizing the fuel feed from the shift reactor 5 in afirst region in communication with the inlet manifold 122 a, having itscatalyst regenerated by the oxidant gas from the oxidant supply 7 in asecond region in communication with the inlet manifold 124 a, and beingcooled by the cooling gas from the supply 8 in third region incommunication with the inlet manifold 132 a. Moreover, as the catalystbody is rotated, the areas of the catalyst body 104 a forming the threesealed regions change so that all the areas of the body performoxidation, are regenerated, and then are cooled in sequence and theprocess is then repeated.

A typical material for the gasket members 118 a, 118 b is Teflon®. Thesealing members 116 a, 116 b, in turn, can be formed from Viton®.

FIGS. 4A-4C illustrate detailed cross-sectional views of a secondembodiment of the oxidizer assembly 6 of FIG. 2. These cross-sectionsare taken along the lines 4A-4A, 4B-4B and 4C-4C of FIG. 2. Thisembodiment uses a similar housing, end walls, gaskets and rotating shaftas in the embodiment of FIGS. 3A-3C and these components have beensimilarly numbered. In this case, however, the sealing members 116 a and116 b are not used and the sealing function is realized with catalystbody 104 a itself.

More particularly, as can be seen the catalyst body is segmented intothree separate regions 104 ac, 104 ad, and 104 ae. These regions arecarried by a Y-shaped sealing frame 115 which, typically, can be formedfrom, for example, Teflon® and/or Viton®. The frame 115 has a centralhub 115 a which is attached to the shaft 114 so that the frame and,therefore, the catalyst regions, can be rotated relative to the housing102. Extending from the central hub are three arms 115 b, 115 c and 115d which extend radially outwardly from the hub to the end wall adjacentthe inner wall of the housing 102. The arms 115 b-115 d additionallyextend along the length of the housing from the gasket member 118 a tothe gasket member 118 b, which as shown are thicker in this embodimentthan in the embodiment of FIGS. 3A-3C. With this configuration for thearms, the catalyst regions 104 ac-104 ae are wedge shaped to fit thewedge shaped areas defined by the regions between successive arms.

The arms 115 b-115 d of the Y-shaped frame 115 in this embodiment act asseals to prevent gas being introduced into or exiting from the catalystregions 104 ac-104 ae from mixing with each other. At any given time,therefore, each of the sealed regions 104 ac-104 ae is in communicationwith a different one of the inlets 108 a, 110 a, 112 a and theircorresponding outlets 108 b, 110 b and 112 b of the oxidizer assembly.As a result, like the embodiment of the oxidizer assembly of FIGS.3A-3C, the assembly of FIGS. 4A-4C is simultaneously oxidizing fuel feedfrom the reactor 5 in a first region in communication with the inlet 108a, is being regenerated by the oxidant gas from the supply 7 in a secondregion in communication with the inlet 110 a, and is being cooled by thecooling gas from the cooling gas supply 8 in a third region incommunication with the inlet 112 a. Also, as the catalyst body 104 a isrotated, the three regions are moved so that each communicates with thedifferent inlet and outlet pairs sequentially. Continued rotation of thebody 104 a then repeats this process.

In the embodiment of the oxidizer assembly of FIGS. 4A-4C, the catalystbody is divided or segmented into three equal sections. However, thenumber as well as the dimensions of each section can be varied. Changingthe number and/or dimensions of the catalyst body sections will ofcourse require a corresponding change in the number and/or the angularspacing of the arms of the sealing member 115.

As discussed above, the catalyst body 104 a can be formed from a ceramichoneycomb corderite substrate coated with a catalyst, preferably anM-OMS-2 catalyst. FIG. 5. shows an example of a ceramic honeycombmonolith or substrate of corderite material manufactured by EmpriseCorporation which is suitable for use as the body 104 a. As can be seenin FIG. 5, the substrate 501 has a substantially cylindrical shape and aplurality of pores or cells 501 a extending through the length of thesubstrate. The pores 501 a form a plurality of channels through thelength of the substrate 501 so as to allow gas or liquid to pass fromone end to the other.

An example of a substrate 501 a for use in the oxidizer of FIGS. 3A-3C,is a substrate which is approximately 0.750 inches in diameter and 3inches in length, and having a cross-section with approximately 300 to500 pores or cells per square inch. The cylindrical substrate 501 mayalso be divided into several wedge-shaped segments and used in theembodiment of the oxidizer 6 in FIGS. 4A-4C.

As also mentioned above, the corderite substrate is coated with anM-OMS-2 catalyst to provide the desired catalyst body 104 a. This may beaccomplished by applying the M-OMS-2 catalyst to the ceramic honeycombcorderite substrate using a catalyst binder solution. A typical bindersolution comprises the M-OMS-2 catalyst powder dispersed in acommercially available wetting agent, such as TFE Teflon®. Acommercially available inking agent, such as Polyox™ WSR-301manufactured by Union Carbide Corporation, may be added to increase theviscosity of the binder solution.

Prior to the application of the catalyst binder solution to thesubstrate, it is desirable to pre-wet the corderite material withdeionized water to allow for better flow of the catalyst suspensionthrough the corderite and to delay the absorption of liquid in thebinder solution by the corderite. Additionally, pre-wetting thecorderite substrate before applying the catalyst allows for largeramounts of catalyst to be held by the substrate than if the catalystbinder solution was applied to the substrate when dry. The bindersolution is applied to the corderite substrate by a dipping method or aspraying method so as to coat the inner and outer surfaces of thecorderite substrate.

FIG. 6 shows an SEM representation of an Ag-OMS-2 catalyst coated onto ahoneycomb corderite substrate. As can be seen, the catalyst coating isuniformly distributed on the surface of the substrate.

Catalyst coated honeycomb corderite substrate samples for the catalystbody 104 a have been prepared with approximately 0.44 to 0.51 grams ofM-OMS-2 catalyst. In addition, it is further desirable that theresulting M-OMS-2 catalyst coating on the substrate compriseapproximately 4% binder by weight, and that the capacity of the catalystis approximately 0.125% by weight of carbon monoxide per gram ofcatalyst.

Catalyst coated honeycomb corderite samples prepared as above set forthwere tested in a micro-reactor bed. FIG. 7 shows a graph of performancedata of the coated substrate samples tested using a simulated reformatefuel gas. The simulated reformate gas comprised 2235 ppm of carbonmonoxide, 75% hydrogen, 25% carbon dioxide and 2000 ppm oxygen gas.During the testing, the simulated reformate gas was passed through thesamples at 100° Celsius with a space velocity of 500 h⁻¹. As shown inFIG. 7, the samples tested were capable of converting approximately 85%of carbon monoxide to carbon dioxide, and after approximately 250minutes of operation, the samples were converting over 50% of carbonmonoxide in the simulated reformate.

After being exposed to the simulated reformate gas, these coated sampleshad their catalyst regenerated by passing through the samples aregeneration gas comprising oxygen at 150° Celsius for 30 minutes. Aftereach regeneration cycle, approximately 85% carbon monoxide conversionwas maintained, demonstrating that the catalyst of the coated substratewas able to be fully regenerated after being exposed to the regenerationgas.

FIG. 8 illustrates schematically a typical operating sequence for theoxidizer assembly 6 of FIGS. 2, 3A-3C and 4A-4C where the catalyst usedis an M-OMS-2 catalyst. As shown, the oxidizer assembly 6 ischaracterized as having a reactor zone 136 (defined by the inlet 108 aof the assembly 6 and the corresponding outlet 108 b of the assembly 6and the region of the catalyst body 104 a communicating therewith), aregenerator zone 138 (defined by the inlet 110 a and the correspondingoutlet 110 b of the assembly 6 and the region of the catalyst body 104 acommunicating therewith) and a heat management or cooling zone 140(defined by the inlet 112 a and the corresponding outlet 112 b of theassembly 6 and the region of the catalyst body 104 a communicatingtherewith).

In operation, a reformate or fuel feed comprising more than 2000 ppm ofcarbon monoxide from the reactor 5 is passed through the reactor zone136, where the carbon monoxide in the reformate gas is converted tocarbon dioxide. Particularly, conversion of the carbon monoxide occursvia a sorption-chemical oxidation process which is carried out in twostages, a sorption stage and a chemical oxidation stage. During thesorption stage, carbon monoxide is selectively adsorbed on the metalactive side of the M-OMS-2 catalyst as follows:

M*+CO→CO_(ad)  (5)

The chemical oxidation stage follows the sorption stage, and during thisstage carbon monoxide is chemically oxidized with oxygen present in theOMS tunnels of the catalyst coating and/or provided in the reformategas. Specifically, oxygen is released from the OMS tunnel and carbonmonoxide is oxidized by reacting carbon monoxide with the releasedoxygen to produce carbon dioxide, as follows:

O-OMS-2→OMS-2+½O₂  (6)

CO_(ad)+½O₂→CO₂+Ag*  (7).

In the operation illustrated in FIG. 8, the above-describedsorption-chemical oxidation reaction is carried out at 100° Celsius.Oxidized reformate gas leaving the reactor zone of the oxidizer assembly6 comprises hydrogen rich gas with less than 10 ppm carbon monoxide andis suitable for use in the anode 2 a of the PEM fuel cell 2.

As the region of the oxidizing assembly 6 oxidizes the carbon monoxidein the fuel feed, the catalyst in the region becomes exhausted ordepleted. Rotation of the catalyst body 104 a brings the region to theregenerator zone 138. In the regenerator zone, oxidant from the oxidantsupply 7 is passed through the region, whereby the spent oxygen in thecatalyst coating of that region is replaced. More particularly, oxygensupply in the M-OMS-2 tunnels of the catalyst coating is replenishedthrough the following reaction:

OMS-2+½O₂O-OMS-2  (8).

As shown, this regeneration process is carried out at 150-200° Celsiusfor approximately 15 to 30 minutes.

Before the regenerated region in the catalyst body 104 a may be usedagain in the reactor zone 136, the temperature of the region has to beadjusted to correspond to the temperature of the zone. Accordingly,after undergoing regeneration in the regenerator zone 138, the rotationof the catalyst body 104 a brings the regenerated region to the heatmanagement zone 140.

In the heat management zone 140, the regenerated region of the catalystbody 104 a is exposed to the cooling gas from the cooling gas supply 8to reduce the temperature of the region to that of the reactor zone,i.e., to about 100° Celsius in the illustrated case of FIG. 8. In thiscase also, air at 100° Celsius may be used as the cooling gas. When theregion is cooled to approximately 100° Celsius, it is ready to processadditional reformate or fuel feed gas from the reactor 5 and continuedrotation of the catalyst body 104 a brings the cooled region back intothe reaction zone 136.

As can be appreciated, the rotation of the catalyst body 104 a can becontinuous or intermittent depending upon the application. Also, in thecase of the second embodiment shown in FIGS. 4A-4C, the sizing of theinlets and the outlets and the sizing of the sealed regions has to besuch that at any given time each region communicates with only one inletand its corresponding outlet. This prevents two gases from beingsupplied to a given region and a mixing of the gases.

In all cases it is understood that the above-described arrangements aremerely illustrative of the many possible specific embodiments whichrepresent applications of the present invention. Numerous and variedother arrangements can be readily devised in accordance with theprinciples of the present invention without departing from the spiritand scope of the invention.

1. A method of using a catalyst body able to support gas flowtherethrough and having a catalyst for promoting a catalytic reaction ofa component of a first gas and being able to be regenerated by a secondgas, comprising: providing at least said first gas and said second gas;and repeatedly moving successive parts of said catalyst body intocommunication with said first gas and then into communication with saidsecond gas; wherein: the part of said catalyst body in communicationwith said first gas causes said component of said first gas to bereacted as said first gas passes though and exits the part of thecatalyst body; and the part of said catalyst body in communication withsaid second gas has the catalyst of that part regenerated as said secondgas passes through and exits the part.
 2. A method in accordance withclaim 1, further comprising: providing a third gas; and said repeatedlymoving is carried out by moving successive parts of said catalyst bodyinto communication with said first gas, then said second gas and thensaid third gas.
 3. A method in accordance with claim catalyst 2, whereinsaid repeatedly moving is carried out such that successive parts of saidcatalyst body are simultaneously in communication with said first,second and third gases.
 4. A method in accordance with claim 3, whereinsaid parts of said catalyst body in communication with said first secondand third gases are sealed from each other so as to inhibit mixing ofsaid first, second and third gases.
 5. A method in accordance with claim4, wherein said first gas is a hydrogen containing gas and saidcomponent is carbon monoxide; said second gas is an oxidant gas; andsaid third gas is a cooling gas.
 6. A method in accordance with claim 5,wherein: said catalyst is M-OMS-2.
 7. A method in accordance with claim6, wherein said M-OMS-2 catalyst is one of Cu-OMS-2, Co-OMS-2 andAg-OMS-2.
 8. A method in accordance with claim 7, wherein said catalystbody is formed from ceramic corderite structure having pores and coatedwith said catalyst.
 9. A method in accordance with claim 8, wherein thetemperature of said first gas is approximately 100° Celsius, thetemperature of said second gas is approximately is between 150 and 200°Celsius and the temperature of said third gas is approximately 100°Celsius.
 10. A method in accordance with claim 9, further comprisingsupplying the first gas after passage through said catalyst body to theanode section of a PEM fuel cell.
 11. A method in accordance with claim1, wherein said parts of said catalyst body in communication with saidfirst and second gases are sealed from each other so as to inhibitmixing of said first and second gases.
 12. A method in accordance withclaim 11, wherein said catalyst is M-OMS-2.
 13. A method in accordancewith claim 12, wherein said M-OMS-2 catalyst is one of Cu-OMS-2,Co-OMS-2 and Ag-OMS-2.
 14. A method in accordance with claim 13, whereinsaid catalyst body is formed from ceramic corderite structure havingpores and coated with said catalyst.
 15. A method in accordance withclaim 14, wherein said first gas is a hydrogen containing gas and saidsecond gas is an oxidant gas.
 16. A method in accordance with claim 15,further comprising supplying the first gas after passage through saidcatalyst body to the anode section of a PEM fuel cell.
 17. A method inaccordance with claim 1, further comprising supplying the first gasafter passage through said catalyst body to the anode section of a PEMfuel cell.
 18. A catalyst body for use in an fuel cell system, saidcatalyst body being formed from a ceramic corderite structure havingpores and coated with a catalyst.
 19. A catalyst body in accordance withclaim 18, wherein said catalyst is M-OMS-2.
 20. A catalyst body inaccordance with claim 19, wherein said M-OMS-2 catalyst is one ofCu-OMS-2, Co-OMS-2 and Ag-OMS-2.
 21. A catalyst body in accordance withclaim 20, wherein said ceramic corderite structure is elongated betweenfirst and second ends and said pores extend between said first andsecond ends.
 22. A catalyst body in accordance with claim 21, whereinsaid ceramic corderite structure includes approximately 300 to 500 poresper square inch.
 23. A catalyst body in accordance with claim 19,wherein: said catalyst body includes a plurality of parts, each of saidplurality of parts being adapted to pass a gas therethrough, and saidcatalyst body is adapted to repeatedly move successive parts of saidplurality of parts into communication with at least a first gas and asecond gas.
 24. A catalyst body in accordance with claim 23, whereinsaid plurality of parts are sealed from each other so as to inhibitmixing of said at least first and second gases.
 25. A method of making acatalyst body for use in a fuel cell system comprising: preparing asolution of a binder and an M-OMS-2 catalyst; applying said solution toa ceramic corderite structure having pores to coat said structure.
 26. Amethod in accordance with claim 25, wherein said solution includes oneor more of a wetting agent and a inking agent.
 27. A method inaccordance with claim 26, wherein said wetting agent is TFE Teflon® andsaid inking agent is Polox WSR-301.
 28. A method in accordance withclaim 25, further comprising applying a wetting agent to said ceramiccorderite structure prior to applying said solution to said ceramiccorderite structure.
 29. A method in accordance with claim 28, whereinsaid wetting agent is deionized water.
 30. A method in accordance withclaim 25, wherein said coating contains approximately 4% binder byweight.
 31. A method in accordance with claim 25, wherein said catalystfacilitates oxidation of carbon monoxide; and the capacity of saidcatalyst is approximately 0.125% by weight of carbon monoxide per gramof catalyst.